The subject matter disclosed herein relates to gas turbines. More particularly, the subject matter relates to transition piece assemblies in gas turbines.
In a gas turbine, a combustor converts chemical energy of a fuel or an air-fuel mixture into thermal energy. The thermal energy is conveyed by a fluid, often compressed air from a compressor, to a turbine where the thermal energy is converted to mechanical energy. Increased conversion efficiency leads to reduced emissions, such as reduced nitrous oxide emissions. Several factors influence the efficiency of the conversion of thermal energy to mechanical energy. The factors may include blade passing frequencies, fuel supply fluctuations, fuel type and reactivity, combustor head-on volume, fuel nozzle design, air-fuel profiles, flame shape, air-fuel mixing, flame holding and gas flow leakages between components. For example, leaks in flow of air from the compressor discharge casing side of the combustor through the interface between the transition piece(s) and the stage one turbine nozzle(s) can cause increased emissions by causing air to bypass the combustor resulting in higher peak gas temperatures. Leaks may be caused by thermal expansion of certain components and relative movement between components. Accordingly, reducing gas leaks in the assembly between the transition piece and nozzle can improve efficiency and performance of the turbine.